You weren’t wrong in your impression though. Jeff Nuttall, who played Gustave LaRoche in 1996, was apparently in poor health and died in 2004 at the age of 70.
Man, that is insane. Not sure I saw much of the third season, but the Gustave LaRoche I am familiar with is a completely different person, who was born 7 months after Robbie Coltrane, rather than 19 years earlier, and is still around.
Yes, there were two different actors who played the character. Nuttall played him for six episodes in 1996. Ian McNeice, who is still alive at 72 (his birthday was two weeks ago), played the character for three episodes in 1994. This means McNeice was 44 and Nuttall was 63 when they appeared on the show.
According to the not-always reliable Showbiz News, actor Ted White, who played Jason in Friday the Thirteenth: The Final Chapter, dies peacefully at 96.